Hearing

Hearing is the ability to perceive sound.

HARVARD GRANT STUDY

The Grant Study of Adult Development began in 1938 and continued for 75 years, making it the longest-running longitudinal study of human development ever undertaken. Its subjects consisted of 268 men who graduated from Harvard in the years of 1939–1944. Researchers analyzed the men, measuring a range of traits including IQ, relationship status, drinking habits, physical traits and more. The intent of the study was to examine happiness and healthy aging, and to identify factors that contribute to a healthy and happy life.

The Grant study was conceived by a physician named Arlie Bock (1888–1984) and his patron W.T. Grant. Bock saw scientific research as putting too much focus on studying illness, and sought to analyze what he referred to as “normal young men” in an effort to gain insight into what constitutes a healthy life.

At the beginning of the experiment the participants were subject to extensive physical measurements, thorough psychological testing and EEG measurements of their brain activity. Throughout the 75-year study they returned for regular medical exams, psychological tests, questionnaires, and interviews. Researchers collected a massive amount of data on the participants. Criticism of the study points to the fact that all the participants were white men. Some of the participants went on to notable careers in politics, most famous among these was President John F. Kennedy.

George Vaillant (1934–), the Harvard psychiatrist who directed the study from 1972 to 2004 later wrote a book about its findings entitled Triumphs of Experience. In his book Vaillant reveals many of the study's compelling findings about the nature of health and aging. He points out that while the subject of adult development later in life—between ages of 30 to 80—is often overlooked, it is an important part of the aging process, noting that many of the study's participants developed new hobbies and skills later in life.

The study put a strong emphasis on marriage and the predictors of healthy relationships. Vaillant sought to measure the “warmth of relationships” of the men in the study. He found that the 58 men who scored highest on the measurements of “warm relationships” (WR) had greater professional success and earned an average of $141,000 a year more during their peak salaries (between ages 55–60) than the 31 men who scored the lowest in WR. The importance of “warmth” in relationships also extends back to childhood. Individuals who had warm relationships with their mothers tended to have higher incomes and were less likely to develop dementia, and those who had had warm relationships with their fathers during childhood reported greater “life satisfaction” at age 75. However, the results also demonstrated that recovery from a difficult childhood is possible—the study shows that the effects tend to fade as a person reaches middle age.

Researchers also emphasize important findings concerning the negative effects of alcohol on marital and lifetime success and happiness. Alcohol was the single strongest cause of divorce among the men studied.

The data produced by the study reveals some surprising findings regarding sex in relation to political beliefs. As the participants of the study aged, the liberal individuals tended to have much more sex than their conservative counterparts, who tended to cease being sexually active around age 68. “I have consulted urologists about this,” Vaillant writes. “They have no idea why it might be so.”

The Grant Study of Adult Development demonstrates the importance of behavior and life choices on longterm happiness and health. The results suggest that while genetics play a role in longevity, our behavior and habits may have an even greater effect, particularly the lifestyle choices people make in midlife, such as drinking.

Vaillant's own summation of the findings of the Harvard Grant Study were as follows: “The seventy-five years and twenty million dollars expended on the Grant Study points to a straightforward five-word conclusion: Happiness is love. Full stop.”

As the oval window vibrates from the increased pressure, the fluid in the coiled, tubular cochlea (inner ear) begins to vibrate the membrane of the cochlea (basilar membrane) which, in turn, bends fine, hairlike cells on its surface. These auditory receptors generate miniature electrical forces that trigger nerve impulses. The nerve impulses travel via the auditory nerve, first to the thalamus and then to the primary auditory cortex in the temporal lobe of the brain. Here, transformed into auditory but meaningless sensations, the impulses are relayed to areas of the brain that convert them into meaningful sounds by examining the activity patterns of the neurons, or nerve cells, to determine sound frequencies. Although the ear changes sound waves into neural impulses, it is the brain that actually “hears,” or perceives the sound as meaningful.

Pitch (how high or low a tone sounds) is a function of frequency. Sounds with high frequencies are heard as having a high pitch; those with low frequencies are heard as low-pitched. The normal frequency range of human hearing is 20–20,000 Hz. Frequencies of some commonly heard sounds include the human voice (120 to approximately 1,100 Hz), middle C on the piano (256 Hz), and the highest note on the piano (4,100 Hz). Differences in frequency are discerned, or coded, by the human ear in two ways, frequency matching and place. The lowest sound frequencies are coded by frequency matching, duplicating the frequency with the firing rate of auditory nerve fibers. Frequencies in the low to moderate range are coded both by frequency matching and by the place on the basilar membrane where the sound wave peaks. High frequencies are coded solely by the placement of the wave peak.




Decibel ratings and hazardous level of noise





Decibel ratings and hazardous level of noise

KEY TERMS

Basilar membrane—
A stiff structure within the inner ear's cochlea that serves as a barrier between two liquid-filled tubes in the inner ear.
Neural impulse—
A nerve impulse, or an electrical signal along the axon of a nerve.
Sensorineural—
Relating to how a nerve senses perception.

Loss of hearing can result from conductive or sensorineural deafness or damage to auditory areas of the brain. In conductive hearing loss, the sound waves are unable to reach the inner ear due to disease or obstruction of the auditory conductive system (the external auditory canal; the eardrum, or tympanic membrane; or structures and spaces in the middle ear). Sensorineural hearing loss refers to two different but related types of impairment, both affecting the inner ear. Sensory hearing loss involves damage, degeneration, or developmental failure of the hair cells in the cochlea's organ of Corti, and neural loss involves the auditory nerve or other parts of the cochlea. Sensorineural hearing loss occurs as a result of disease, birth defects, aging, or continual exposure to loud sounds. Damage to the auditory areas of the brain through severe head injury, tumors, or strokes can also prevent either the perception or the interpretation of sound. Regardless of the cause, loss of hearing leads to significant communication problems in those who experience it. Psychologists and other mental health professionals might help people with hearing loss cope with the frustration, embarrassment, or other emotions they initially feel.

Resources

BOOKS

Davis, Lennard J. The Disability Studies Reader. New York: Routledge, 2006.

WEBSITES

Brogaard, Berit. “Do You Really Hear What You Think You Hear?” Psychology Today. https://www.psychologytoday.com/blog/the-superhuman-mind/201502/do-youreally-hear-what-you-think-you-hear (accessed August 4, 2015).

Dewane, Claudia. “Hearing Loss in Older Adults. Its Effect on Mental Health.” Social Work Today. http://www.socialworktoday.com/archive/071510p18.shtml (accessed August 4, 2015).